view contrib/fuzz/fuzzutil.cc @ 38336:bb7e3c6ef592

phabricator: preserve the phase when amending in the Differential fields

I have no idea if it's better to change scmutil.cleanupnodes() so that it has
the option to either apply a specific phase (e.g. for various --secret switches)
or carry over the phase of the old node.  The benefit would be that the caller
doesn't have to remember to do this.  The con is maybe inefficiency?  I wrote
this up as issue5918.  I'm leaving that open since Yuya flagged it as an API
bug.

Since most other callers already do this, it's the simplest fix.  (It's not
obvious that `split`, `fix` and `rebase` are doing this, but there is test
coverage for `fix` and `rebase`, and experimenting with `split` shows it does
the right thing.)

#include "fuzzutil.h"

#include <cstring>
#include <utility>

contrib::optional<two_inputs> SplitInputs(const uint8_t *Data, size_t Size)
{
	if (!Size) {
		return contrib::nullopt;
	}
	// figure out a random point in [0, Size] to split our input.
	size_t left_size = (Data[0] / 255.0) * (Size - 1);

	// Copy inputs to new allocations so if bdiff over-reads
	// AddressSanitizer can detect it.
	std::unique_ptr<char[]> left(new char[left_size]);
	std::memcpy(left.get(), Data + 1, left_size);
	// right starts at the next byte after left ends
	size_t right_size = Size - (left_size + 1);
	std::unique_ptr<char[]> right(new char[right_size]);
	std::memcpy(right.get(), Data + 1 + left_size, right_size);
	LOG(2) << "inputs are  " << left_size << " and " << right_size
	       << " bytes" << std::endl;
	two_inputs result = {std::move(right), right_size, std::move(left),
	                     left_size};
	return result;
}